1. Field of the Invention
The present invention relates to a defect information managing method of managing defect management information recorded in a defect management area in an information recording medium such as an optical disc medium comprising the detect management area. The present invention also relates to an information recording and/or reproducing apparatus for using the information recording medium comprising the defect management area. The present invention further relates to an information reproducing apparatus for using the information recording medium comprising the defect management area.
2. Description of the Related Background Art
An information recording or storage medium such as an optical disc medium of a type has a user area for storing user data and a reserved spare area. The optical disc medium of the type described has a defect area occurring in the user data area. An information recording and/or reproducing apparatus for using the optical disc medium carries out a replacement process for replacing the above-mentioned defect area into a wholesome area in the spare area. Defect management information related to the replacement process is stored in an area which is called a defect management area (DMA). High reliability is required to the DMA.
Replacement information is added to the defect management information every time the replacement occurs and it is necessary to renew or update the defect management information to be recorded in the DMA. A frequency of rewriting or updating the defect management information in the DMA is relatively high. Among information recording media, a DVD-RAM allows 100,000 or more times rewriting for the DMA. In addition, the high reliability is ensured by recording a set of the defect management information having the same contents in four locations of the DMA. On the other hand, in the information recording medium having a low level of resistant to the rewriting, measures are proposed, for example, in Japanese Unexamined Patent Publications Tokkai Nos. 2004-39076 and 2004-288285, namely, JP2004-39076A and JP2004-288285A which will hereinafter be called first and second prior art documents, respectively. The first and the second prior art documents correspond to United States Patent Application Publication Nos. 2004/0057357 and 2004/0257933, namely, US2004/0057357 A1 and US2004/0257933 A1, respectively.
In the first prior art document, an information storage or recording medium comprises first through M-th DMA sequences each of which comprises first through N-th DMAs, where M represents a first positive integer which is not less than two and N represents a second positive integer which is not less than two. The first positive integer M may be equal to four while the second positive integer N may be equal to one hundred. Herein, n-th DMAs in the first through the M-th DMA sequences are collectively called an n-th DMA set, where n represents a variable between one and N, both inclusive. The first through the N-th DMA sets are collectively called a group of DMA sets. In the group of DMA sets, one of the first through the N-th DMA sets is used as a currently active DMA set. A set of the latest defect management information is always stored in the currently active DMA set. That is, it will be assumed that the currently active DMA set is the n-th DMA set. In this event, the latest defect management information is stored in the n-th DMAs of the first through the M-th DMA sequences. Reliability with respect to the defect management information is ensured by using a different DMA set (e.g., an (n+1)-th DMA set) in the group of DMA sets when the currently active DMA set (e.g., the n-th DMA set) degenerates caused by repetition of the rewriting into a defective one.
More specifically, in order to improve the fault tolerance of DMAs, when the currently active DMA set has weakened, a set of the latest defect management information stored in the currently active DMA set (the n-th DMA set) is shifted to a new DMA set (the (n+1)-th DMA set). It is determined that the currently active DMA set has weakened when the overwrite count for the currently active DMA set approaches an allowable overwrite count of media having the group of DMA sets, or when defects on the currently active DMA set increase to result in more likely failing error correction for the currently active DMA set.
The DMA has a size of an integer multiple of that an ECC (error correction code) block as a true recording unit in a drive. On the DVD-RAM, one ECC block consists of sixteen sectors, and the ECC block has a size of thirty-two KB. Each DMA is made up of a DDS/PDL ECC block and a SDL ECC block, “PDL” is an abbreviation for Primary Defect List while “SDL” is an abbreviation of Secondary Defect List. The PDL is a list for registering primary defect information indicative of primary defects while the SDL is a list for registering secondary defect information indicative of secondary defects. Specifically, the PDL registers the primary detect information associated with the primary detects found in certification executed upon formatting a medium. In comparison with the PDL, the SDL registers the secondary detect information associated with the secondary defects found upon normal recording (e.g., upon recoding user data). The defect management information includes a replacement source address and a replacement destination address. In each of the first through the M-th DMA sequences, the first through the N-th DMAs are sequentially allocated and one of the first through the N-th DMAs is used as the currently active DMA in turn from the first DMA to the N-th DMA in ascending order. In other words, one of the first through the N-th DMA sets is used as the currently active DMA set in turn from the first DMA set to the N-th DMA set in ascending order.
More specifically, the information storage or recording medium comprises the first through the M-th DMA sequences each of which comprises the first through the N-th DMAs, in the manner which is described above. In other words, each of the first through the M-th DMA sequences comprises N DMAs from the first DMA to the N-th DMA. The first through the N-th DMAs in the first through the M-th DMA sequences are collectively called the first through the N-th DMA sets, respectively. The first through the N-th DMA sets are collectively called the group of the DMA sets. If the first DMA set is used as a currently active DMA set, the second through the N-th DMA sets are auxiliary or backup ones.
The first through the N-th DMA sets are used in turn from the first DMA set to the N-th DMA set in ascending order. In an initial state, the first DMA set is used as the currently active one and the second through the N-th DMA sets are not used or backup ones. When detects on the first DMA set increase or when the overwrite count has exceeded a prescribed value, the first DMA set is changed from the currently active one to a used one, and a set of the latest defect management information stored in the first DMA set is replaced to and recorded on the second DMA set. Likewise, using the third through the N-th DMA sets in turn, even when each DMA set has suffered detects or overwrite damages, the information storage or recording medium can be continuously used without breaking down as a system.
On the other hand, in the second prior art document, an information storage or recording medium comprises not only the group of DMA sets but also a group of selection information area (SIA) sets for recording selection information indicative of a location or an address of the currently active DMA set in the group of DMA sets in which a set of the latest defect management information is stored. In addition, the second prior art document discloses a method of specifying, in a short time, the currently active DMA set in which a set of the latest detect management information is stored.
Specifically, the selection information is called a DMA manager in the second prior art document. The selection information area (SIA) is called a manager storage area in the second prior art document. The second prior art document discloses an information storage or recording medium comprising a rewritable area, which comprises first through M-th DMA sequences, first through P-th manager storage area sequences (SIA sequences), and a user area, where P represents a third positive integer which is not less than two. Each of the first through P-th SIA sequences stores identical selection information. As a result, the fault tolerance of the SIAs can be improved. The first positive integer M may be equal to four while the third positive integer P may be equal to two.
More specifically, the first and the second DMA sequences are allocated on a lead-in area on the innermost periphery of the information storage or recording medium while the third and the fourth DMA sequences are allocated on a lead-out area on the outermost periphery of the information storage or recording medium. Each of the first through the fourth DMA sequences comprises first through N-th DMA reserved areas. The first through the N-th DMA reserved areas correspond to the first through the N-th DMAs of the information storage or recording medium disclosed in the above-mentioned first prior art document, respectively. Herein, n-th DMA reserved areas in the first through the fourth DMA sequences are collectively called an n-th DMA set. In an initial state, each of the first DMA reserved areas (the first DMA set) contained the respective DMA sequences stores current (the latest) defect management information. If the first DMA reserved area contained in an arbitrary DMA sequence (e.g., the first DMA sequence) falls under a defective area, a set of the defect management information stored in the first DMA set is transferred to the second DMA set.
As described above, on the information storage or recording medium disclosed in the second prior art document, currently active DMA reserved areas change or transit. Based on this, the second prior art document introduces the DMA manager used to quickly search the first through the N-th DMA sets for the currently active DMA set. That is, the information storage or recording medium disclosed in the second prior art document comprises the first through the P-th manager storage areas (SIAs) for storing DMA managers (selection information). Each DMA manager manages the addresses of the currently active DMA reserved areas or the currently active DMA set. In other words, each manager storage area is a location information area for storing the location information of the currently active DMA reserved areas.
It will be assumed that the third positive integer P is equal to two. In this event, the first manager storage area sequence is located on the lead-in area while the second manager storage area sequence is located on the lead-out area. Each of the first and the second manager storage area sequences stores identical location information. Each of the first and the second manager storage area sequences comprises first through K-th manager reserved areas, where K represents a fourth positive integer which is not less than two. This is to take a measure against defects of the DMA manager. The fourth positive integer K may be equal to ten.
In other words, in the second prior art document, the information storage or recording medium comprises the plurality of SIAs as well as the plurality of DMAs. The information storage or recording medium comprises first through P-th SIA sequences each of which comprises first through K-th SIAs. The first through the P-th SIA sequences correspond to the first through the P-th manager storage area sequences, respectively. The first through the K-th SIAs correspond to the first through K-th manager reserved areas, respectively. Herein, k-th SIAs in the first through the P-th SIA sequences are collectively called a k-th SIA set, where k represents a variable between one and K, both inclusive. The first through the K-th SIA sets collectively called a group of SIA sets. In the group of SIA sets, one of the first through the K-th SIA sets is used as a currently active SIA set. A set of the latest selection information (a set of latest DMA managers) is always stored in the currently active SIA set. That is, it will be assumed that the currently active SIA set comprises the k-th SIA set. In this event, a set of the latest selection information (a set of the latest DMA managers) is stored in the k-th SIAs of the first through P-th SIA sequences. Reliability with respect to the selection information (a set of the DMA managers) is ensured by using a different SIA set (e.g., a (k+1)-th SIA set) in the group of SIA sets when the currently active SIA set (e.g., the k-th SIA set) degenerates caused by repetition of the rewriting into a defective one.
More specifically, in order to improve the fault tolerance of SIAs, when the currently active SIA set has weakened, a set of the latest selection information (a set of the latest DMA managers) stored in the currently active SIA set (the k-th SIA set) is shifted to a new SIA set (the (k+1)-th SIA set).
In the initial stage, the first manager reserved areas contained in the respective manager storage area sequences store a set of the location information indicative of locations of the currently active DMA reserved areas or the currently active DMA set. As a result of overwrite accesses, when the first manager reserved area contained in a given manager storage area sequence (e.g., the first manager storage area sequence) falls under a defective area, all pieces of location information stored in the first manager reserved areas of the first and the second manager storage area sequences are changed (transferred) to the second manager reserved areas of the first and the second manager storage area sequences. At any rate, the DMA manager manages the addresses of the currently active four DMA reserved areas.
More specifically, in the initial state, the latest DMA managers are stored in the first manager reserved areas of the respective manager storage area sequences. When one or more of the first manager reserved areas in the manager storage area sequences fall under defective areas, the latest DMA managers are transited to the second manager reserved areas in the manager storage area sequences. Likewise, transition of the DMA managers is made in turn. When the DMA managers reach the K-th manager reserved areas in the manager storage area sequences, the recording operation is inhibited.
It is assumed that the information storage or recording medium disclosed in the second prior art document allows up to 1000 overwrite accesses. In addition, it is assumed that on this information storage or recording medium, registration of 10000 cases of defect management information is realized. Under the circumstances, in this case, if DMAs are transited every 1000 accesses, the medium can proof registration of 10000 cases of defect management information by 10 (=10000/1000) transitions in principle. That is, by allowing the DMA replacement process, poor overwrite characteristics can be overcome.
The second prior art document also discloses the information recording and/or reproducing apparatus which supports both a table lookup scheme and an incremental scheme as a scheme for searching for the currently active DMAs. The table lookup scheme searches for the currently active DMAs based on the DMA managers. If the DMA managers cannot be read out, the currently active DMAs are searched by the incremental scheme. The incremental scheme checks all DMA reserved areas contained in the DMAs in turn to search for the currently active DMAs. In other words, the incremental scheme is used as recovery of the table lookup scheme if the table lookup scheme fails.
At first, the currently active DMA reserved areas are searched by the table lookup scheme. That is, if location information indicative of the currently active DMA reserved areas can be read out from the latest DMA manager areas, the currently active DMA reserved areas can be found out. If any currently active DMA reserved areas cannot be found by the table lookup scheme, the currently active DMA reserved areas are searched by the incremental scheme.
However, the second prior art document neither discloses nor teaches how to search for the currently active SIA set in which a set of the latest selection information (a set of the latest DMA managers) is stored. More specifically, it will be assumed that a plurality of DMA manager sets (a plurality of pieces of selection information) are stored in the group of SIA sets. In this event, the second prior art document dose not establish a procedure for selecting the latest selection information by searching for the currently active SIA set and a method of using the latest selection information. In addition, it will be assumed that there is no unassigned or future-usable DMA set in lieu of the currently active DMA set. Under the circumstances, it is impossible to avoid to fall into a situation where the defect management information cannot be extract caused by degradation of an active DMA set in the first and the second prior art documents. Furthermore, each of the first and the second prior art documents neither discloses nor teaches decision criteria for changing the currently active DMA manager set (the currently active SIA set) into a different DMA manager set (different SIA set) when contents of the currently active DMA manager set are renewed.
In addition, Japanese Unexamined Patent Publication Tokkai No. 2005-56542, namely, JP2005-56542A (which will hereinafter be called third prior art document) discloses a write-once information storage or recording medium permitting to easily search for the latest DDS and the latest defect list. Disclosed in the third prior art document, the write-one information storage or recording medium comprises a lead-in area, a data area, and a lead-out area. The lead-in area comprises first and second defect management areas and a group of defect management work areas. The data area includes a user data area and a spare area. The lead-out area comprises third and fourth defect management areas. The group of defect management work areas comprises a plurality of defect management work areas. Each defect management work area is an area for temporality recording defect management information renewed or updated before the write-one information storage is finalized. On the defect management work area, a disc definition structure (DDS) and a defect list are arranged. The latest defect list and the latest DDS are located in a recorded defect management work area contiguous to the boundary of recorded defect management areas and unrecorded defect management areas in order of the latest defect list and the latest DDS along a predetermined direction.
However, the third prior art document neither discloses nor teaches a selection information area (a DMA manager area) for storing selection information (a DMA manager) for specifying a location of the currently active DMA in which the latest defect management information is stored.